I-12 industrial oil is a general purpose oil with no additives. It is made from sweet crude by selective purification. This oil is used for lubrication of bushings of straight bar and linking machines, spindles of metal cutters, bearings of low power electric motors, and as an operating liquid in positive displacement of hydraulic drives operated indoors. Combined purification methods of I-12 industrial oil are based on simultaneous influence of several electrical fields or a field with filtration. The principle of combining electric field influence and centrifical force is implemented in cyclone separators and centrifuges equipped with a special electrical device. By design, a triboelectric centrifuge purifier is a multifoil rosette with two chargers that create opposite charges in the industrial oil. The passes through the swirler in a translational-rotational movement. It them passes the oil through a circular ring space. Due to friction with barriers, contaminants become oppositely charged. Centrifugal force moves particles with a positive charge to the outlet wall where they are coagulated with negatively charged particles. The charges are neutralized in the coagulated particles. Then by the force of gravity and inertia, the particles are deposited in a special settling tank. Comparing hydrocycling efficiency with that of a similar machine equipped with chargers, the chargers are 40% more efficient on average. When using centrifuges with electrifying devices, the electric field may be obtained by voltage from an external source or by a triboelectric effect. The triboelectric effect occurs due to rotor friction against special bars. The rotor is made from a special dielectric material. (Plexiglas, PTFE, or some other dielectric material ) It is also possible to combine centrifugal force with a magnetic field. It is done by installing permanent magnets into centrifuge systems to capture ferromagnetic particles. Diamagnetic and paramagnetic contaminants are only influenced by the centrifugal force. The most widespread of combined industrial oil purification systems are devices combining elecrtric fields and filtration effects. These include magnetic filters, filtering centrifuges and vibration (acoustic) filters. In centrifuge filtration, the centrifuges operate at relatively low rotation speeds. Contaminants may be removed from the rotor either continuously or occasionally. A magnetic filter is free from such a disadvange of magnetic purifier as selective removal of only ferromagnetic particles. Such devices, beside permanent magnets, use special filters capturing non-magnetic contaminants. An additional filter element (usually a metal mesh) protects the surfaces of the magnets from tar, sediment and other products of hydrocarbon oxidation. In vibration filters the oil passes through a vibrating porous membrane. The vibrations prevent sedimentation of contaminants on the surface and reduce hydraulic losses, increasing the filter’s service life. It should be noted that the combined methods of purifying oil products are not widely used at this time due to the complexity of purifier design.